-LRB- Health.com -RRB- -- Will placing a tea bag on a cold sore make it disappear ? Can you ease hot flashes with herbs ? And does putting yogurt on your nether parts have a prayer of curing a yeast infection ?

It used to be that you 'd hear about these kinds of home remedies from your mom . These days , they 're touted on websites , blogs , and online forums . In fact , 61 percent of American adults turn to the Internet to find help in treating what 's ailing them , a 2009 study reveals .

But do these natural moves actually work ... and , just as important , could they do more harm than good ? Health asked medical experts to weigh in on the Internet 's most popular home cures .

The online claim : Yogurt can stop a yeast infection

Is it true ? No

Yeast infections -- and their symptoms , from intense vaginal itchiness to cottage cheese-like discharge -- are caused by an overgrowth of the fungus candida . Because studies show that yogurt can promote the growth of healthier strains of bacteria in the stomach and intestines , people have long assumed it might also keep candida in check . And that rumor keeps circulating , thanks to the Internet .

Unfortunately , `` no study shows conclusively that eating yogurt cures or even lessens the severity of yeast infections , '' says Michele G. Curtis , M.D. , professor of obstetrics and gynecology at the University of Texas Medical School at Houston .

Neither will douching with yogurt , or -LRB- yikes ! -RRB- dipping a tampon in the stuff , freezing it , and inserting it -- a remedy suggested on some websites . In fact , douching can cause yeast infections , Curtis says , especially if you 're using yogurt ; its sugars could actually help yeast grow .

If you 're sure you have a yeast infection , based on a past experience , Curtis recommends using an over-the-counter medication , such as Monistat . But , she points out , `` everything that itches is not yeast ! '' So see your gyno when in doubt : That itching might actually be bacterial vaginosis , for instance , which requires treatment with antibiotics .

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The online claim : Black cohosh eases hot flashes

Is it true ? Yes

Commonly known as bugwort or rattle root , this herb is derived from a plant called Actaea racemosa . While it may sound like something from Harry Potter 's wizarding world , this remedy is not all hocus-pocus : Some studies suggest that black cohosh may indeed reduce hot flashes , according to guidelines re-released last year by the American College of Obstetricians and Gynecologists .

`` It appears to have an anti-inflammatory effect , '' says Philip Hagen , M.D. , co-editor of the `` Mayo Clinic Book of Home Remedies . '' In fact , the herb is often prescribed in Europe ; it 's a key ingredient in Remifemin , a popular drug there , which is also available in the United States .

While U.S. studies have n't conclusively proven that black cohosh works , Curtis says it ca n't hurt to try the herb -- just consult with your doctor about the dosage first , and stick with it for 12 weeks , she says . -LRB- Make sure you 're getting black cohosh , not blue cohosh , which could potentially be harmful , she adds . -RRB-

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The online claim : Pop calcium pills to quell PMS cramps

Is it true ? Yes

Since there 's scientific evidence that PMS sufferers have lower levels of calcium in their blood , it 's not a stretch to think that loading up on it would ease the cramps , headaches , and bloating that come at that time of the month . Indeed , research has shown that taking 600 milligrams of calcium twice a day can reduce PMS symptoms .

And getting the nutrient in your food -LRB- such as calcium-packed dairy -RRB- may keep them at bay altogether : In a recent study conducted at the University of Massachusetts , Amherst , women who consumed four servings a day of skim or low-fat milk reduced their risk of developing PMS by 46 % .

Note : Some women 's cramps are so severe that only prescription medication can curb them , Curtis says . So if calcium does n't make a difference with yours , see your doctor .

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The online claim : Tea tree oil can zap your zits

Is it true ? Maybe

One brand of tea tree oil sold online is dubbed `` Pure Liquid Gold , '' and it just may be , at least in the case of acne . A study published in the British Journal of Dermatology found that applying the extract to pimples reduced inflammation .

`` Tea tree oil is antifungal and antibacterial , '' says Debra Jaliman , M.D. , a New York City-based dermatologist . `` It 's so effective that many of my patients prefer it to benzoyl peroxide . ''

Other experts are not so keen . `` The oil can cause rashes and even blistering , '' warns Jerome Z. Litt , M.D. , assistant clinical professor of dermatology at Case Western Reserve University School of Medicine in Cleveland and the author of `` Your Skin from A to Z. '' If you 're nervous about using tea tree oil , Jaliman says , instead try a face wash for oily skin that contains salicylic or glycolic acid .

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The online claim : Steam clears up sinus headaches

Is it true ? Yes

This old-school treatment -- touted in more than 400,000 Google results ! -- really works . `` Inhaling steam flushes out your nasal passages , relieving sinus pressure , '' explains Neil Kao , M.D. , head of research at the Allergic Disease and Asthma Center in Greenville , South Carolina .

Add a few drops of peppermint or eucalyptus oil to make it more potent . `` The minty smell causes a tingling sensation in the nasal membrane , and this has a decongestant effect , '' says Kao , who also suggests dabbing Vicks VapoRub at the lower rim of your nostrils .

Another natural alternative : Using a neti pot to irrigate the nostrils with saline solution , which can also ease sinus symptoms , according to one study .

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The online claim : Black tea bags help cold sores disappear

Is it true ? No

If left alone , cold sores usually clear up in a few weeks -- but who wants to wait ?

Online remedies for the blisters range from the absurd -LRB- like earwax -RRB- to the less silly , like placing a damp black tea bag on the sore . `` Black tea leaves have tannins , compounds that may inhibit the growth of viruses and bacteria , but no studies have verified this , '' Hagen says .

Tea bags may also have an anti-inflammatory effect , he says . But your best bet to shorten healing time is an OTC treatment like Abreva or a prescription med like Valtrex . To prevent sores from popping up , stay out of the sun , and use a high-SPF sunscreen around your lips : `` Sun-light can trigger cold sores if you 're prone to them , '' Hagen says .

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The online claim : Drinking cranberry juice prevents UTIs

Is it true ? Yes

This popular home cure is n't just an old wives ' tale : Major medical institutions , including the National Institutes of Health , agree that drinking cranberry juice can be effective for treating urinary tract infections -LRB- UTIs -RRB- . `` The berries contain proanthocyanidins , which keep E. coli from attaching to the bladder wall and causing an infection , '' Hagen says .

If you 're prone to UTIs , drink one to two glasses of cranberry juice daily to help prevent them . Doing so also works when you have symptoms -- like a constant need to pee , or a burning sensation when you do -- to speed recovery . -LRB- There 's also evidence that peeing immediately after sex can help prevent UTIs by flushing out bacteria . -RRB-

Stick to juice that 's at least 20 % pure cranberry -- or try supplements , taking up to six 400-milligram pills twice a day an hour before or two hours after a meal . If your symptoms do n't end within 24 to 48 hours , see your physician -- especially if you have a fever or chills . `` That points to something serious , '' Hagen says , `` and means you should not be messing with a home remedy . ''

Copyright Health Magazine 2011

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Medical experts weigh in on the Internet 's most popular home cures

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Yogurt does n't cure yeast infests , nor does black tea bags help cold sores disappear

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Some oils , herbs and juices can help treat your ailments